Photothermographic materials are well known in the photographic art. Photothermographic materials are also known as heat developable photographic materials. The photothermographic materials after imagewise exposure are heated to moderately elevated temperatures to produce a developed image without the need for processing solutions or baths. Examples of known photothermographic materials are described in, for example, Research Disclosure, Vol. 170, June 1978, Item No. 17029.
Photographic materials for producing silver images and dye images are also well known. For example, a photothermographic element for producing a silver image and dye image is described in Research Disclosure, Vol. 185, September 1979, Item No. 18535. In such a photothermographic element a reducible organic silver salt upon heating in a first silver image-forming layer is reduced in the exposed areas of the photothermographic element and releases at least part of the salt anion which transfers to a second cobalt (III) amine complex containing layer. The salt anion which transfers to the second layer is believed to initiate a dye-forming reaction between the cobalt (III) amine complex and phthalaldehyde. The photothermographic element does not involve or suggest a melt former-silver solvent which is capable of promoting dye formation more efficiently in photothermographic elements designed to produce silver images and dye images involving photographic silver salts and cobalt (III) amine complexes.
Cyclic imides, such as succinimide, have been used in photothermographic silver halide materials as toners, such as described in Research Disclosure, Vol. 170, June 1978, Item No. 17029 to help provide a more neutral (black) silver image. However, such photothermographic silver halide materials have not involved such cyclic imides to aid dye formation.